Reaction substructure searching in search.php.
Now we can do "exact" search matching by InChI. Remains to be seen how well it works with complicated strucs.
Treat structure queries with multiple reactants/products as AND queries. Add similarity searching using Tanimoto comparison on FP2 fingerprints. Needs UI cleanup and docs and possible bug fixes; in progress.
Clean up chemistry options input and validate tanimoto input.
Merge branch 'search' into develop

* search:
  Clean up chemistry options input and validate tanimoto input.
  Treat structure queries with multiple reactants/products as AND queries. Add similarity searching using Tanimoto comparison on FP2 fingerprints. Needs UI cleanup and docs and possible bug fixes; in progress.
  Now we can do "exact" search matching by InChI. Remains to be seen how well it works with complicated strucs.
  Reaction substructure searching in search.php.